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Title:APPLYING THE GRAIN-BOUNDARY DIFFUSION PROCESS USING ELECTROPHORETIC DEPOSITION TO SELECTED REGIONS OF A Nd-Fe-B MAGNET
Authors:Goričar, Blaž (Author)
Kristl, Matjaž (Mentor) More about this mentor... New window
McGuiness, Paul (Co-mentor)
Files:.pdf MAG_Goricar_Blaz_2014.pdf (4,38 MB)
MD5: D2AADA3108C020E81920705BF91DDC9C
 
Language:English
Work type:Master's thesis/paper (mb22)
Typology:2.09 - Master's Thesis
Organization:FKKT - Faculty of Chemistry and Chemical Engineering
Abstract:This Master's thesis research is about the localized coercivity enhancement of Nd-Fe-B magnets, which are used in electric motors. Computer simulations show, that when magnets operate at high temperatures, they experience large demagnetizing fields. However, this happens only on specific parts of the body of the magnet. The demagnetization can be prevented by locally enhancing the coercivity only on these specific parts. The goal of this Master’s thesis was to research the localized coercivity enhancement by creating a magnet, where one half would have different magnetic properties compared to the other half. Commercially available Nd-Fe-B magnets were bought from Shin-Etsu, Japan. The magnetic properties of the magnets were measured on two very different devices – the permeameter and the vibrating sample magnetometer. The demagnetization curves were compared. The coercivity of the magnet was improved with the electrophoretic deposition of dysprosium on the surface. The dysprosium then diffused, at high temperature, from the surface to the inside of the magnet along the grain boundaries. The microstructure of the magnet was analysed on the scanning electron microscope, while the content of the elements was quantitatively analysed with the EDS method. The demagnetization curves of both devices were comparable. The grain-boundary diffusion process of dysprosium with the electrophoretic deposition increased the coercivity of the magnet by 25 %, without any significant loss in remanence. The research on the localized grain-boundary diffusion was first done with measurements on the vibrating sample magnetometer and then confirmed with the Hall probe. We discovered that one part of the magnet could have different magnetic properties compared to the other half. There was a clear border between the two.
Keywords:Nd-Fe-B magnet, coercivity, magnetic properties, electrophoretic deposition, grain-boundary diffusion process.
Year of publishing:2014
Publisher:[B. Goričar]
Source:Maribor
UDC:537.363:537.62(043.2)
COBISS_ID:18247958 New window
NUK URN:URN:SI:UM:DK:V55HOY1D
Views:1636
Downloads:94
Metadata:XML RDF-CHPDL DC-XML DC-RDF
Categories:KTFMB - FKKT
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Secondary language

Language:Slovenian
Title:UPORABA PROCESA ELEKTROFORETSKEGA NANAŠANJA Z DIFUZIJO V MEJAH KRISTALOV NA IZBRANIH MESTIH Nd-Fe-B MAGNETOV
Abstract:Magistrsko delo vsebuje raziskave o lokalnem izboljšanju koercitivnosti Nd-Fe-B magnetov, ki se uporabljajo v elektromotorjih. Računalniške simulacije kažejo, da kadar magneti obratujejo pri visokih temperaturah, pride do razmagnetenja, ki se pojavlja samo na določenih mestih magneta. Razmagnetenje lahko preprečimo tako, da izboljšamo koercitivnost samo na teh določenih mestih magneta. Cilj magistrskega dela je bila raziskava o lokalnem izboljšanju koercitivnosti z izdelavo magneta, kjer je imela ena polovica magneta drugačne magnetne lastnosti kot druga polovica. Komercialno dosegljive Nd-Fe-B magnete smo kupili od podjetja Shin-Etsu iz Japonske. Naprej smo izmerili magnetne lastnosti magnetov na dveh napravah, ki delujeta po različnem principu – permeametru in magnetometru s tresočim vzorcem. Dobljene krivulje razmagnetenja smo primerjali med seboj. Koercitivnost magneta smo izboljšali s procesom elektroforetskega nanašanja disprozija na površino. Disprozij je pri visoki temperaturi difundiral s površine v notranjost magneta skozi kristalne meje. Mikrostrukturo magneta smo raziskali na vrstičnem elektronskem mikroskopu, vsebnost elementov pa smo kvantitativno analizirali z metodo EDS. Krivulje razmagnetenja dobljene na obeh napravah so bile med seboj primerljive. Proces difuzije skozi kristalne meje disprozija z elektroforetskim nanašanjem je izboljšal koercitivnost magnetov za 25 %, brez izgube remanence. Raziskavo o lokalni difuziji skozi kristalne meje smo najprej opravili z meritvami na magnetometru s tresočim vzorcem in nato še potrdili z meritvami s Hallovo sondo. Ugotovili smo, da ima lahko ena polovica magneta drugačne magnetne lastnosti v primerjavi z drugo polovico. Meja med obema polovicama je bila jasno določena.
Keywords:Nd-Fe-B magnet, koercitivnost, magnetne lastnosti, elektroforetsko nanašanje, difuzija skozi kristalne meje.


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